Cons of Geothermal Energy

There are some minor environmental issues associated with geothermal power.

Geothermal power plants can in extreme cases cause earthquakes.

There are heavy upfront costs associated with both geothermal power plants and geothermal heating/cooling systems.

Very location specific (most resources are simply not cost-competitive).

Geothermal power is only sustainable (renewable) if the reservoirs are properly managed.

Advantages of Geothermal Energy

1. Environmentally Friendly

Geothermal energy is generally considered environmentally friendly. There are a few polluting aspects of harnessing geothermal energy (read more about them in the disadvantages section), but these are minor compared to the pollution associated with conventional fuel sources (e.g. coal, fossil fuels)

The carbon footprint of a geothermal power plant is minimal. Further development of our geothermal resources is considered helpful in the fight against global warming.

An average geothermal power plant releases the equivalent of 122 kg CO2 for every megawatt-hour (MWh) of electricity it generates – one eight of the carbon emissions associated with a typical coal power plant.

2. Renewable

Sustainable is another label used for renewable sources of energy. In other words, geothermal energy is a resource that can sustain its own consumption rate – Unlike conventional energy sources such as coal and fossil fuels. According to scientists, the energy in our geothermal reservoirs will literally last billions of years.

3. Massive Potential

Worldwide energy consumption – about 15 terawatts (TW) – is not anywhere near the amount of energy stored in earth. However, most geothermal reservoirs are not profitable and we can only utilize a small portion of the total potential. Realistic estimates for the potential of geothermal power plants vary between 0.035 to 2 TW.

Geothermal power plants across the world currently deliver about 10,715 megawatts (MW) of electricity – far less than installed geothermal heating capacity (about 28,000 MW).

4. Stable

Geothermal energy is a reliable source of energy. We can predict the power output of a geothermal power plant with remarkable accuracy. This is not the case with solar and wind (where weather plays a huge part in power production). Geothermal power plants are therefore excellent for meeting the base load energy demand.

Geothermal power plants have a high capacity factor – actual power output is very close to total installed capacity.

The global average power output was 73% (capacity factor) of total installed capacity in 2005, but as much as 96% has been demonstrated.

5. Great for Heating and Cooling

We need water temperatures of more than 150°C (about 300°F) or greater in order to effectively turn turbines and generate electricity with geothermal energy.

Another approach is to use the (relatively small) temperature difference between the surface and a ground source. The earth is generally more resistant to seasonal temperature changes than air. Consequently, the ground only a couple of meters below the surface can act as a heat sink/source with a geothermal heat pump (much in the same way an electrical heat pump works).

We`ve seen a tremendous growth in the number of homeowners that utilize geothermal heating/cooling in the last couple of years.

Disadvantages of Geothermal Energy

1. Environmental Issues

There is an abundance of greenhouse gases below the surface of the earth, some of which mitigates towards the surface and into the atmosphere. These emissions tend to be higher near geothermal power plants.

Geothermal power plants are associated with sulfur dioxide and silica emissions, and the reservoirs can contain traces of toxic heavy metals including mercury, arsenic and boron.

Regardless of how we look at it, the pollution associated with geothermal power is nowhere near what we see with coal power and fossil fuels.

2. Surface Instability (Earthquakes)

Construction of geothermal power plants can affect the stability of land. In fact, geothermal power plants have lead to subsidence (motion of theearth’s surface) in both Germany and New Zealand.

Earthquakes can be triggered due to hydraulic fracturing, which is an intrinsic part of developing enhanced geothermal system (EGS) power plants.

Just a couple of years ago (January 1997), the construction of a geothermal power plant in Switzerland triggered an earthquake with a magnitude of 3.4 on the Richter scale.

3. Expensive

Commercial geothermal power projects are expensive. The exploration and drilling of new reservoirs come with a steep price tag (typically half the costs). Total costs usually end up somewhere between $2 – 7 million for a geothermal power plant with a capacity of 1 megawatt (MW).

As previously mentioned, most geothermal resources cannot be utilized in a cost-effective manner, at least not with current technology, level of subsidies and energy prices.

The upfront costs of geothermal heating and cooling systems are also steep. On the other hand, these systems are likely to save you money years down the line, and should therefore be regarded as long-term investments. Ground source heat pumps typically costs $3,000 – $10,000 and have a payback time of 10 – 20 years.

4. Location Specific

Good geothermal reservoirs are hard to come by. Some countries have been blessed with great resources – Iceland and Philippines meets nearly one third of their electricity demand with geothermal energy.

If geothermal energy is transported long distances by the means of hot water (not electricity), significant energy losses has to be taken into account.

5. Sustainability Issues

Rainwater seeps through the earth’s surface and into the geothermal reservoirs over thousands of years. Studies show that the reservoirs can be depleted if the fluid is removed faster than replaced. Efforts can be made to inject fluid back into the geothermal reservoir after the thermal energy has been utilized (the turbine has generated electricity).

Geothermal power is sustainable if reservoirs are properly managed. This is not an issue for residential geothermal heating and cooling, where geothermal energy is being used differently than in geothermal power plants.

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The bottom line is this: Geothermal energy is generally regarded as environmentally friendly, sustainable and reliable. This makes geothermal energy a no-brainer in some places, but heavy upfront costs stops us from realizing the full potential.

How much influence geothermal power will have on our energy systems in the future depends on technological advancements, energy prices and politics (subsidies). No one really knows what the situation will look one or two decades down the line.

You might want to compare this article to the rest of the pros and cons series:

Comments

Geothermal is always promoted as being very clean and green. This is not entirely true. While it is certainly clean, it is merely a heat transfer process. It brings heat from the inside the earth to the surface of the earth where is it converted to electricity. It does not contribute in any way to increasing greenhouse gasses but it does increase the warming of the surface of the planet. The heat being used would have remained under the earth’s surface but geothermal processes would bring this heat to the surface where it would remain and contribute to global warming. Of course this is inconsequential if it is implemented in small ways. But it should probably keep us from ever developing it on a large scale.

Please understand what you are talking about before rendering opinions. First off there are two types of “geothermal” systems, true geothermal and heat pumps. True geothermal uses the earth’s inner heat that has been generated by radiation from the core. Think volcanoes and Old Faithful. True, this can and does bring more heat to the surface, but it statistically is inconsequential when referencing global warming. The direct and local affect on purge water in large power plants using geothermal can be a problem though.

The second type uses latent energy that has been stored in the soil directly from the sun. Using this heat will NOT affect global warming at all because it naturally conduct and transfer to the atmosphere anyhow. Now, greenhouse gasses… where do you think the electricity comes from to generate the energy to run the heat pump? Fossil fuels mostly, aka greenhouse gases. True it doesn’t burn anything locally, but that doesn’t mean that geo’s have a net zero carbon footprint. You are purchasing electricity that has been made from the burning of natural gas and coal.

Why are you here? If you honestly think that then you are what is wrong with the world today. Global warming is happening and it is going to pose a real threat in the immediate future. If we don’t start taking steps to change what we are doing immediately, we are going to have a serious, serious problem on our hands. You should go and do a some research on this subject and then see how you feel once you realize what is happening.

However, I don’t think this heat contribution is significant to global warming. Here’s why:

-If we are talking about geothermal electricity generation, most of the heat is used to generate electricity (the rest being loss due to inefficiency).

-We may be worse off by not using geothermal energy, e.g. heating houses with electricity compared to waste water from geothermal power plants.

It is true that by harnessing geothermal energy, there is a net increase in surface temperature, as well as a net decrease in temperature under the surface. I’m curious whether there are any sources stating that this contributes in any significant way to global warming?

I’ve sold geothermal systems in Michigan long before working with dehumidification and indoor pools. In all honesty and I have asked the question numerous times; as energy efficient etc. as it is, States offering incentives and lower utility rates etc. to use it…. let’s also not forget just how much coal is burned to produce that electricity. I’m a strong believer in cycles and not global warming… what about the ice age? Global cooling? It’s all cyclical and yes we do need to pay attention, but when people start talking global warming, I say follow the money.
As for geo, I use it.. however, I am well aware that coal is being burned in many areas to provide electricity. There is no free lunch!

Hi Chris, I’m with you on the Global Warming garbage, yes let’s follow the money. I don’t believe it either, and no I’m not mentally challenged, I feel that the earth has cycles like you say, the Ice age is a good example, now we are going to be the hot planet; I know we can help the earth by keeping it clean, our water clean, and other stuff we can do to help the earth. I don’t know who started the Global Warming but I wish it would stop, but people do believe in global warming, this is only my opoin.

If you actually look at the Earth’s geological history, you’ll notice that it has natural heating cycles caused by nature. STATISTICS have shown that we are currently in a heating period that will be followed by a cooling(most likely a nice age). There are graphs on almost every unbiased website like the EPA’s that show this. This means that while greenhouse gases may be impacting the Earth’s global average temperature, they probably aren’t the main issue.

global warming is from the energy we create to heat r houses, find the oil to drive r cars and the cars them selves and the computer am on the world is the same temp for billions of years, until we started polluting the atmosphere, look at china where all the shit we buy is made POLUTION! All the stuff we use and own have created carbon dioxide and all contributing to depleting the ozone layer.
Its not geo thermal that doing it, a 6 inch hole 250′ feet in the ground is like saying your fart is causing global warming

Your comments in cons for geothermal say that the intitial cost is steep and will be a long term payback while your solar cons say initial cost is somewhat or fairly steep and will take a few years to pay back.

Geothermal heat pumps are much more economical (quicker payback) than solar due to its reliability for base load and working 24/7/365. Your comments seem to have a solar bias as many people do. The geothermal uses stored solar energy from the ground to heat your home. It is just a solution for the solar/thermal storage challenge. Don’t down play a more reliable solution just because it is not as visable as solar or wind.

I have to debate the topic and unfortunatly, I have to take the con side. This has helped a bit, but I heard something about companies trying to dig where the heat source is too deep causing the ground to heave making buildings fall and destroying towns. Is that true?

I think it depends on the situation. Svartsengi Geothermal Power Station in Iceland is located right next to a big bathing Resort (Blue Lagoon) without any adverse effects.

Geothermal power plants do release carbon dioxide (CO2) and hydrogen sulfide (H2S), which both can be dangerous for people. Arsenic, mercury, lithium and boron can contaminate drinking water.

There are safety features around geothermal power plants that should minimize these issues. Contacting the company behind the geothermal power plant directly would be the best thing to do to learn more about this.

how you guys were able to keep the pros and cons discussion/debate, in particular for geothermal,along non-party-political partisan ilnes was a treat in itself; you see. we in little Dominica, 289 sq miles, aka known as The Nature Isle of the Caribbean are currently exploring energy independence via geothermal.

There are criticisms of geothermal energy tapping which prevent its being implemented on the large scale which it should be. Critics say that study and research to find a resourceful area is too costly and takes up too much time. Then there is more great expense needed to build a geothermal power plant, and there is no promise of the plant turning a profit. Some geothermal sites, once tapped, might be found to not produce a large enough amount of steam for the power plant to be viable or reliable. And we hear from the environmentalists who worry that bringing up magma can bring up potentially harmful materials along with it.

I don’t leave a bunch of responses, however i did a few searching and wound up here Geothermal Energy Pros and Cons – Energy Informative.
And I do have a couple of questions for you if you usually do not mind.

Could it be just me or does it look like some of the responses look like
they are written by brain dead individuals?
😛 And, if you are writing at additional places, I would like to follow anything new you have to post.
Could you make a list of the complete urls of your communal
pages like your linkedin profile, Facebook page or twitter feed?

Nice article! I am doing comparison research on solar and wind vs. geothermal. It would be nice to see a pros and cons list with new geo-technology (closed loop systems) like “Lightning-Dock” in southern New Mexico. I think it would make a stronger case for geothermal!

Aw, this was an exceptionally nice post. Finding the time and actual effort to produce a very good article… but what can I say… I put things
off a whole lot and never manage to get nearly anything done.

I was under the impression that the earth’s heat is primarily left over from its creation and partially sustained through friction and radioactive decay. And that the earth’s core has been gradually cooling since its birth. Logically we know the core is currently in balance, or at least not heating up, so actively taking heat away would cause a cooling effect. how long until we worry about “core cooling” and the demise of the Van Allen belts?

My small Island country is on the verge of completing a geothermal energy project, we have over 9 volcanoes, hundreds of rivers, a large boiling lake and tons of hot springs. I’ve read lots of concerns with regard to global warming, toxins being released from the earth and cooling of the earths core etc. which I believe to be all nonsense. Yes global warming is real but in the context of heat being released from the earth that is not what global warming is… its gasses released into the atmosphere that prevent the earth from releasing heat from the sun. concerning the toxins this is normal, minimal and relatively insignificant as it relates to other forms of electrical production. I am concerned however with regard to how the water is returned back into the soil. We have an abundant yearly rainfall but based on the potential use of the plant I’m not sure it will be enough to replenish what is removed in the long term. We have also experienced a few earthquakes as well as a river drying up completely since the project began.

Global Warming is caused when Carbon is released into the atmosphere which strengthens the Ozone Layer. The suns rays enter the earth and bounce back, but when they bounce back towards space, they get trapped by the Ozone Layer. The heat realesed from the geothermal plants plants will heat up the earth by a bit, but the important thing is that it is not adding to the Ozone Layer. Humanity is destined to leave Earth, at the rate at which the planet is heating from the burning of fossil fuels is estimated, Earth will become too hot in 50-200 hundred years, since we keep increasing our emition of fossil fuels yearly. This will give humanity more time, a possibly technology would eliminate the problem all together. About the budget, if we can make a, if you will, a super powerplant, by combining solar, hydro, biomass, wind, and Geothermal energy. One profit from a energy source could cover the cost of a bigger more expensive power source. To solve the substaniable issue, what makes the water hot? The ground. For every gallon of water we pump up, we pump down another gallong, let’s say from the ocean. The water will come down in the form of precipitation and replenish the water source. Once you have the hot water, you pump it into a chamber where their is a liquid with a low boiling point that’s steam would turn the turbines. Of course this fuid would have to enviromently friendly. Go Geothermal!!!!
-Jack

For those of you who do not believe in the current trend of the earth warming up relatively rapidly, please take into account the following; 1. How long did it take evolution of the earth to create the carbon deposits ? 2. The very carbon deposits we are depleting in a matter of how many years ? and 3. Don’t you think that releasing these carbon side products , that took billions upon billions of years to form, in only few years (in geological time) to convert cause serious problems ? May I suggest that (certain) commenters refrain from being ignorant and make statements on that basis?

I would like to fix a few things. When I said that Carbon is strengthening the ozone layer, I meant it is weakening the ozone layer which lets in harmful radiation from the sun that can cause cancer. The Carbon spreads around the planet like a blanket, capturing the solar heat that would otherwise be radiated out into space, hence the term “Global Warming.” The method I was talking about where water is pumped down is called Enhanced Geothermal System (EGS). Also the last topic I talked about is called Binary System. A fluid that would work is called Isobutane which has a boiling point of -11.7 degrees Celsius or 10.94 degrees Fahrenheit. And screw burning biomass as part the “Super Power Plant” Because it is not environmentally friendly.
-Jack